Research Progress in Preparation and Functionalization Applications of Clay Mineral Films

Clay mineral membranes, derived from naturally abundant layered silicates, such as montmorillonite, vermiculite and kaolinite, have emerged as a revolutionary class of functional materials, due to their unique structural and physicochemical properties. These membranes exhibit high specific surface areas, tunable nanochannels, exceptional chemical stability and environmental compatibility, making them highly promising for applications in water purification, molecular separation, ion transport and energy conversion. The inherent cation-exchange capacity, self-repairing ability and surface wettability modulation further enhance their adaptability in complex environments. However, challenges, such as scalability in fabrication, long-term stability under harsh conditions and precise control over nanoscale functionalities, necessitate systematic research to unlock their full potential.

This paper is beginned with an overview of preparation methods for clay mineral nanosheets, encompassing mechanical exfoliation, chemical exfoliation and liquid-phase exfoliation techniques. Subsequently, fabrication approaches for clay mineral membranes were systematically reviewed, including casting, dip-coating, spray-coating, vacuum filtration, electrophoretic deposition and 3D printing, while evaluating their advantages and limitations. For instance, vacuum filtration, the most widely adopted method, enables facile fabrication of smooth well-laminated membranes, but is restricted to liquid suspensions and may induce disordered stacking of nanosheets during thick-film preparation. Subsequently, the distinctive functional properties of clay mineral membranes are thoroughly evaluated. (1) Surface wettability can be modulated via ion exchange, chemical functionalization and environmental conditions. (2) Permeability, governed by particle size, pore architecture, and interlayer structure, is tunable through chemical strategies such as crosslinking agents and cation intercalation. (3) Swelling resistance is enhanced via acid modification, cation crosslinking and nanoscale reinforcement to mitigate hydration-induced layer expansion. (4) Self-healing mechanisms enable physical and ionic conductivity restoration. Furthermore, recent advancements in applications are highlighted, particularly in molecular sieving, pollutant removal, ion-selective transport, and nanofluidic energy harvesting.

As a class of 2D nanomaterials derived from natural layered silicates and clay mineral membranes demonstrate remarkable structural tunability, high surface area and eco-friendly characteristics, positioning them as promising candidates for industrial wastewater treatment, desalination and precision separation. Despite significant progress in fabrication and structural engineering, critical challenges remain, such as controllable synthesis of homogeneous nanosheets with minimized defects and tailored interlayer charge distribution, scalable production for industrial deployment, long-term stability under extreme operational conditions, necessitating advanced anti-swelling strategies. Future efforts should focus on optimizing nanosheet exfoliation, developing cost-effective large-scale fabrication techniques and elucidating degradation mechanisms to advance their practical implementation. With continued innovation, clay mineral membranes are poised to bridge the gap between laboratory-scale research and real-world environmental and energy applications.